This paper proposes a novel spoke-type permanent magnet (PM) motor with auxiliary salient poles (ASPs). With these ASPs, unequal ASPs and shifted ASPs in the circumferential direction can be realized and combined to reduce the torque pulsation, while their functions are different. Unequal ASPs are employed to eliminate the second-order torque pulsation. Nevertheless, the shifted ASPs are selected to reduce the first-order torque pulsation. Additionally, the relationship between the unequal angle or shifted angle of the ASPs and the order of the torque pulsation is revealed. Furthermore, the revealed principle of torque pulsation reduction can be extended to other slot-pole combinations. Finally, a prototype is manufactured for experiments to evaluate the low torque pulsation spoke-type PM motor. Through theoretical analysis and experimental testing, it is verified that the proposed motor offers low torque pulsation and that the revealed principle for torque pulsation reduction of different orders is feasible and effective.

This paper proposes a comprehensive multi-objective optimization design method for a new spoke-type permanent magnet (PM) machine with auxiliary salient poles (ASPs) for the improvement of torque performance. The key of this method is to consider the deterministic and robust performances simultaneously. First, the sensitivity analysis is adopted to classify design parameters into different levels and the corresponding optimization techniques are skillfully employed to realize the trade-off design based on the appropriate model constructed by the response surface methodology (RSM). However, inevitable perturbations especially during the mass production will result in big fluctuations of torque performances and affect the reliability and quality of the machine, which are often neglected in deterministic design. Therefore, a robust design method, i.e., the design for six sigma (DFSS), is presented to address the parametric uncertainties. Afterward, the Monte Carlo analysis (MCA) is used to obtain the statistic samples and the barebones multi-objective particle swarm optimization (BB-MOPSO) algorithm is employed to find the robust optimal solution. The corresponding electromagnetic performances and reliability of the products are compared and analyzed. Finally, a prototype is manufactured and tested to verify the validity of the proposed optimization design method.

Both of consequent-pole permanent magnet (CPM) motor and spoke-type PM motor have the potential to reduce the consumption of PMs while suffering from the high torque pulsation. This paper proposes a new hybrid rotor CPM motor, in which the hybrid rotor is composed of consequent-pole surface-mounted PM (SPM) modules and spoke-type PM rotor modules. Compared with the existed hybrid rotor CPM motor with half of spoke-type PM rotor modules, the whole of spoke-type PM rotor modules and their shifting are capable to adjust the harmonics of the rotor-MMF, which is the benefit to improvement of the torque performances. To obtain high torque performances and low PM volume, multi-objective optimization is employed to optimize the key parameters. Afterward, the proposed motor is compared with three PM motors. The results show that compared with the SPM motor, the proposed CPM motor offers high PM torque and PM utilization ratio like other CPM motors. Besides, the torque pulsation is reduced significantly compared with the traditional CPM motor. Hence, the proposed motor offers a high PM utilization ratio and low torque pulsation simultaneously. Through the finite element method (FEM) analysis and experimental test, the merits of the proposed hybrid CPM motor are verified.

This paper takes a new spoke-type flux-modulation (STFM) machine with inverted T-shape permanent magnets as the research object and proposes a multi-objective optimization design method based on air-gap flux density harmonics to improve the torque and torque ripple. The key of the proposed method is to optimize the overall torque performance by improving the contribution of main air-gap harmonics to torque and torque ripple. The working harmonic expression of the machine is firstly obtained based on the magnetomotive force (MMF) -permeance model due to the new rotor structure make the working harmonics are different from the existing flux-modulation PM machine. Then, the torques generated by the 11th and 31st air-gap harmonics and the torque ripple generated by the 29th air-gap harmonics are taken as sub-objectives. Furthermore, the response surface analysis (RSM) and the barebones multi-objective particle swarm optimization (BB_MOPSO) algorithm are combined to optimize three sub-objectives. The overall torque and torque ripple are improved due to the optimization of three sub-objectives. Moreover, the 20-slot/11-pole pair traditional model is used as a benchmark to verify the performance of the investigated machine. Finally, a prototype is manufactured and tested to verify the correctness of the theoretical analysis.

This paper proposes a method to reduce the torque pulsation of the three-phase fractional-slot concentrated-winding (FSCW) interior permanent magnet (IPM) motor by lowering sub-harmonics. The key principle of this method is the selection of an optimized six-layer winding with different numbers of conductors. Firstly, the interaction of stator-rotor magnetomotive force (MMF) which contributes to the torque pulsation is analyzed. Additionally, the relationship between sub-harmonics (1st sub-harmonic and 2nd sub-harmonic) and torque pulsation orders is revealed. Then, different numbers of conductors are adopted in coils to eliminate the 2nd sub-harmonic. Nevertheless, the 1st sub-harmonic increases in the two-layer and four-layer windings. Therefore, the optimized six-layer winding is employed to suppress the 1st sub-harmonic and ensure that the 2nd sub-harmonic is zero. Besides, there are almost no other harmonics except the main harmonic and slot harmonics in the proposed IPM motor. Hence, the torque pulsation can be greatly reduced even under different current angles. Furthermore, the principle for torque pulsation reduction by lowering sub-harmonics is revealed. The effectiveness of the proposed method is verified through the comparisons with finite element analysis and experimental test.

This article proposes a new fault-tolerant rotor permanent magnet flux-switching (FT-RPMFS) motor. The key of the proposed FT-RPMFS (PFT-RPMFS) motor is its new rotor topology with the unique configuration of the auxiliary PM (APM), located in the rotor to enhance the air-gap flux density. Besides, the PFT-RPMFS motor incorporates a union rotor structure, which makes it easy to be manufactured and strengthens its mechanical robustness when compared to the conventional FT-RPMFS (CFT-RPMFS) motor with a segregated rotor part, and therefore, the CFT-RPMFS motor is used as a benchmark to prove the performance of the PFT-RPMFS motor. For fair analysis and comparison, all the design parameter dimensions and materials are the same in both the CFT-RPMFS and the PFT-RPMFS motors with the same slot-pole synergy of 20-slot/11-pole. Furthermore, a multi-objective optimization technique is adopted to improve the output torque and reduce the torque ripple. Moreover, since the FT-RPMFS motor is evolved from a stator permanent magnet flux-switching (SPMFS) motor, the SPMFS motor is also selected as another benchmark to verify the superiority of the PFT-RPMFS motor. Finally, a prototype is manufactured and tested to verify the correctness of the theoretical analysis.